In recent years, the effective use of a so-called white space, which is generated by reallocation of broadcast frequency bands, is actively discussed. The white space is a part of a broadcast frequency band that can also be used for other purposes because of geographical condition and time condition.
Using the white space, for example, an area broadcast system which is an area-limited broadcast system has been suggested.
FIG. 1 is a figure showing forms of usage of a frequency band for the area broadcast system. As shown in FIG. 1, forms of usage of a frequency band include five forms, e.g., a full segment type, a Null-attached one-segment (1seg) type, a one-segment (1seg) type, a multi-one segment (taba-seg) type, and separate segment (bara-seg) type.
For example, the multi-one segment (taba-seg) type is a form of broadcast, in which only one-segment (1seg) portion is extracted from a frequency band (6 MHz, 13 segments) for one channel of digital terrestrial television broadcast, and it is connected with one-segment (1seg) portions of other channels and the one-segment (1seg) portions are broadcast in a frequency band for one channel.
On the other hand, the separate segment (bara-seg) type is a form of broadcast that is done with a shift of the central frequency (the segment position) of a frequency bandwidth of 468 kHz, which is the same as the one-segment (1seg) type.